"The judicial review brought by the applicants is an attempt to undermine human rights protection in Indonesia," said the Community Legal Aid Institute, a non-governmental organisation, in a statement.

"We hope that in the future the Constitutional Court can maintain its role as a negative legislator and will not bow to pressure from various groups that act in the name of religious morality," it said.

Indonesia is the world's largest Muslim-majority country, where many see sex outside of marriage as taboo.